Piezo Electric Pressure Sensor/Transmitter
Most pressure sensors on the market deploy a piezo crystal to measure pressure. Optical and capacitive sensors are also available but less common. All pressure sensors need to be immersed/inserted into a fluid to be able to measure. This means the plumbing system either needs to be opened or a tee needs to be installed at some endpoint of a plumbing branch or twig. Pressure sensors come in ranges, so it’s important to pick the right range for the application. Output is typically a 4-20 mA, a voltage signal or serial communication.
Differential Pressure Sensor/Transmitter
Like the pressure sensors above, the differential pressure sensor uses the same method but employs two sensors (sometimes only one) arranged to be able to measure a pressure difference. This can be useful in HVAC systems or to measure pressure drops in systems. They are not the same as two pressure sensors placed individually as typically, they have a connecting tube or pipe. Output is typically a 4-20 mA, a voltage signal or serial communication.